1. Field of the Invention
The present invention relates to devices for bracing pipes and other loads, suspended below floors and ceilings, against sway and seismic disturbances, and, in particular, to a bar joist clamp for firmly gripping a building support, such as a bar joist, and other flanged structures.
2. Background of the Related Art
There is a multitude of products in the market utilized by building and plumbing contractors for bracing and supporting pipes, ducts, sprinkler systems, fans, air-conditioners and other loads below floors and ceilings. These products include clamps, braces, hooks, straps, plates, brackets, among other items. Typically, one end of a brace is attached to the load while the top end is attached to a beam on a floor or a ceiling. In many instances, a floor or ceiling is resting on a parallel arrangement of building supports, such as bar joists. A bar joist generally comprises two pairs of spaced angle irons with each pair being coupled to one another by a generally triangular arrangement of tubular struts or arms. The floor or ceiling rests on the horizontal flanges of the top angle iron pair while the arms originate in the space between the inner vertical flanges. The bottom angle iron pair is essentially a mirror image of the top.
It is usually difficult to firmly and reliably place a strong clamp, for attachment to the top end of the brace, on the top angle iron pair of the bar joist since the horizontal flanges are inaccessible for clamping and the vertical flanges are generally fairly closely spaced. Though the horizontal flanges of the bottom angle iron pair of the bar joist present a convenient clamping surface it is usually not desirable to support heavy loads from the bottom angle iron pair. In the prior art, typically, a stud is welded to one of the flanges of the top angle iron pair of the bar joist. The brace is then attached to the welded stud using a combination of appropriate attachment components. The stud welding is time consuming, requires a trained professional and the use of welding equipment, all of which undesirably add to the cost. Additionally and disadvantageously, the stud welding usually requires a precise predetermination of the positioning of the stud and does not permit any flexibility in adjustment of the welded stud's location, thereby possibly requiring repetitive welding, and hence resulting in wasteful expenditure.
Thus, there is a need for a bar joist clamp which can not only withstand substantial loads, but is also simply and expeditiously installable and adjustable, and is preferably economical to manufacture, thereby being desirably inexpensive in cost and in use.